package com.practice.bootdemo.common;

/**
 * @author :Administrator
 * @description: TODO edit class Description
 * @create date: 2020/4/5 21:56
 */
public class TestA {
    public static void main(String[] args) {
        String ss=null;
        if (ss!=null&&ss.contains("a")){
            ss="ok";
        }
        System.out.println(ss);
    }
}
